The invention relates generally to mass storage systems, and in particular, to visualization of logical volumes at the host front end and storage back end of a mass storage controller.
To meet the growing data storage needs of today's computer systems, and, simultaneously to enable more than one computer processor to access the same stored data, disk drive controllers have been configured to have two or more independent storage ports, that is, two or more ports through which different computer processors (host computers) can access the same mass storage device(s). The mass storage device(s) can be one or preferably, a plurality, of disk drives configured in accordance with a predetermined or selectable structure.
In a typical disk drive system, large disk drive memories are typically divided into a plurality of logical volumes. Thus, a single disk drive can have 4, 8, or more logical volumes. In addition, each of the logical volumes can be accessed by plural host computers. Thus, for example, one host computer may be responsible for writing and maintaining a database in a first logical volume on the disk drive and other host computers ordinarily only expect to read the database for their varying purposes and applications. Other host computers may be responsible for yet other logical volumes.
In addition, various logical volumes may be protected in different ways. Thus groups of logical volumes may be written in accordance with a RAID (redundant array of independent disks) protocol, an n-way mirrored protocol such as that used in the EMC Symmetrix.RTM. system, or the logical volume may not be protected at all. When a logical volume is protected, it is typically written to different disk drives. This is all performed transparently to the host computer or processor, which identifies the logical volume with its own designation. The disk drive controller system, may, however, employ different identifications for each of the logical volumes and transparently access the data as requested by the host computer, in accordance with an internal protocol being used for the logical volume. Internally, the logical volumes are often referred to as logical devices to distinguish between a host designation and a controller assigned designation.
In any case, the host computers are not aware of which disk drive or disk drives store the data, which is being sent to or retrieved from the mass storage system. Thus, it may occur by chance or happenstance that the load balance to the disk drives is poor, which can result in substantial delays and slower throughput as some channels become clogged while others remain relatively free.
At present, various tools exist which enable a user to identify which host designated logical volumes are written at which host ports of the controller, and which device logical volumes (or logical devices) are identified at the various disk ports of the storage controller. This information has been typically available as raw data to the maintenance engineers, not to the users, and even when available to the user, was presented in such a poor manner that the user, with only great difficulty, if at all, through manual manipulation, would have a clear understanding of the load balancing or other distribution of the logical volumes between various host ports and the disk drive storage elements.